Treatment assembly seal



July 1, 1969 W.C.HUGHES ETAL 3,453,642

y TREATMENT ASSEMBLY SEAL W/Y//m C Hqges, Raymond W /1 w72,

777 e/'* orwey July l, f W, Q HUGHES ETAL 3,453,642

' TREATMENT ASSEMBLY SEAL Filed Aug. 25, 1966 /27 Ver? ons.' W/Y//m C, Hag/72.5. Raymond MA1/nz,

United States Patent O 3,453,642 TREATMENT ASSEMBLY SEAL William C. Hughes, Scotia, N.Y., and Raymond W. Kunz, Monroe, Conn., assignors to General Electric Company, a corporation of New York Filed Aug. 25, 1966, Ser. No. 584,290 Int. Cl. G0111 15/12 U.S. Cl. 346-17 5 Claims ABSTRACT OF THE DISCLOSURE A treatment system seal comprises a chamber maintained at a first pressure housing a material handling system, a chamber maintained at a second pressure housing a treating medium, and an improved seal assembly for maintaining the pressure differential between the chambers. The improved seal assembly comprises a roller, a closely spaced guide cradl-e with an aperture therethrough, and the interspaced material which is to be treated. The aperture allows for treating medium communication between the material and the chamber housing the treating medium.

'the material to be treated while still allowing communication between the treating medium and the material t be treated. It is also frequently necessary to maintain a substantial pressure differential since the chamber housing the treating medium may require an extremely high or extremely low pressure to function properly. Since ready access to the chamber housing the material is a prerequisite to most systems, the pressure within this chamber will be less extreme. Where the object to be treated is a web or filament, it becomes necessary to maintain a smooth flow of the material past the treating mediummaterial point of communication while maintaining a seal between the two chambers. The smooth flow and the good seal combination have not been achieved in the prior system which failed by allowing displacement of r the material from the communication point, by presenting dificulties in initially threading the material for passage past the communication point, and by making the cleaning of the communication point nearly impossible. Our invention is concerned With a seal assembly which maintains the necessary pressure differential without the above-mentioned problems.

The invention has particular usefulness in various charged particle writing systems where it is necessary to maintain a pressure differential between a chamber housing a charged particle source and a chamber housing a recording tape. The need arises since charged particle writing requires a highly evacuated conduit for passage of charged particles. Without the highly evacuated conduit, ionization of gases within the conduit occurs, and the effectiveness of the charged particle writing is greatly impaired. Prior art charged particle writing systems have always been plagued 'by undesirable restraint on the recording tape. Further problems have existed in the un desirable displacement of the recording tape from the focal plane of the charged particle writing source, in

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the threading of the recording means, and in the cleaning of the region between the chambers.

It is an object of our invention to provide a seal in a treatment system which will allow passage of a material to be treated without undesirable restraint.

It is a further object of our invention to provide a seal which will allow the material to be treated to be maintained in a position for proper communication with the treating medium.

It is a further object of our invention to provide a seal which will allow easy threading of the material to be treated.

It is a still further object of our invention to provide a seal which may be easily cleaned.

Briefly stated, in accordance with one aspect of our invention, we provide a treatment system including a chamber maintained at a iirst pressure housing a 4material handling system, a chamber maintained at a second pressure housing a treating medium, and an improved seal assembly for maintaining the pressure differential between the chambers. The improved seal assembly comprises a roller, a closely spaced guide cradle with an aperture therethrough, and the interspaced material which is to be treated. The aperture allows for treating medium communication between the material and the chamber housing the treating medium.

In accordance with another aspect of our invention, we provide a charged particle writing system including a chamber with a reduced pressure housing a tape handling system, a chamber of a still further reduced pressure housing a charged particle source, and an improved seal assembly maintaining the pressure differential between the chambers. The improved seal assembly comprises a roller, a closely spaced guide cradle with an aperture therethrough, and an interspaced tape. The aperture allows for charged particle communication between the tape and the low pressure chamber housing the charged particle source. The seal assembly may also include a phosphor screen adjacent the guide cradle which may be aligned with the chamber housing the charged particle source to provide a visual display capability.

The specification concludes with claims particularly pointing out and distinctly claiming the subject matter which we regard as our invention. The invention may also be understood from the following description taken in connection with the accompanying drawings in which:

FIGURE l is a cross-sectional View of a seal assembly;

FIGURE 2 is a charged particle writing system;

FIGURE 3 is a seal assembly for maintaining the pressure differential in the charged particle writing system 0f FIGURE 2.

FIGURE 4 is a view of the seal assembly of FIGURE 3 taken along line 4 4; and

FIGURE 5 is a view of the seal assembly of FIGURE 3 taken along line 5-5.

In FIGURE 1, a seal assembly comprising a guide cradle 66, a seal roller 67 maintained in complementary relationship with the guide cradle 66, and the material 65 to be treated interspaced between the guide cradle 66 and the seal roller 67. An aperture 64 in the guide cradle 66 serves as a conduit of communication between the material 65 and a source for a treating medium. The labyrinth formed by the material 65, the accurate surface of the guide cradle 66, and the complementary surface of the seal roller 67 form a seal between a chamber housing the source of the treating medium and a chamber into which the material 65 flows. Since the seal roller 67 is mounted on a shaft 68 and therefore free to rotate, the material 65 may flow freely without undesirable restraint and still maintain the seal. In order to maintain alignment of the material 65 with 63 may be seen as 3 the aperture 64, a circumferential depression 69 is provided.

A more specific aspect of the invention constituting a charged particle writing system is shown in FIGURE 2 and comprises a three chamber unit. A writing tape guide and a labyrinth seal assembly 1 is positioned between an evacuated chamber 2 which houses a charged particle source 20 and a chamber 3 which houses a tape handling system. Charged particles communicate with tape as it passes aperture 4 in guide cradle 6 of assembly 1. In order to maintain a very small clearance between tape 5 and guide cradle 6, seal roller 7 is accurately positioned with respect to cradle 6. The guide cradle 6 and seal roller 7 in combination with tape 5 produce a seal sufficient to maintain a pressure ratio between the chambers 2 and 3 greater than 1:100. The seal roller 7 is flanked by guide rollers 8 and 9 mounted symmetrically on both sides of the guide cradle 6 to assure a smooth ow of tape 5 between seal roller 7 and guide cradle 6. Chamber 3 also contains a plurality of corner guide rollers 10 and a pair of port guide rollers 11 which are positioned adjacent a sealing structure 12. The sealing structure 12 maintains a pressure differential between the chamber 3 and a reel chamber 13. A pair of port guide rollers 14 align tape 5 with reels 15 contained Within reel chamber 13.

The assembly 1 shown in FIGURE 2 is a simplied drawing of the invention. FIGURE 3 reveals assembly 1 in somewhat more detail than shown in FIGURE l and is a view of assembly 1 as seen from the chamber 3.

Since it is imperative that the tape remain aligned with the aperture 4 at all times, two guide posts 48, 49 engage one edge of tape 5 in order to maintain tape 5 guided into depression 16 on seal roller 7. Depressions 16 on guide rollers 8 and 9 serve only to prevent contact between the sensitive surface of tape 5 and the surface of guide rollers 8 and 9. The freely moving seal roller 7 is mounted on a shaft 17 to provide unrestrained revolutions while the flanking guide rollers 8 and 9 are similarly mounted on shafts 18 and 19 inserted in a pair of fixed mountings 50 and 51 as shown in FIGURE 4. The fixed mountings 50 and 51, in combination with caps 39, maintain the rollers 8 and 9 in alignment. As the seal roller 7 revolves about the shaft 17, the tape 5 will pass over the rollers 8 and 9 and between the guide cradle 6 and the seal roller 7 with very little axial displacement.

In order to achieve the objects of easy threading and cleaning, the shaft 17 is mounted in terminal blocks 25 and 26 which are attached to a pivotal support arm 27. The support arm 27 is hinged to a base 38 on a pin 28 allowing the :guide cradle 6 to be exposed during threading or cleaning. After lthreading or cleaning, arm 27 may be pivoted to the operative position effecting contact between the rounded surfaces of terminal blocks 25 and 26 and cradle 6 thereby accurately positioning sealing roller 7 with respect to cradle 6 so that the tape 5 may pass very close to cradle 6 but without contacting it.

In order to maintain support arm 27 in operative position, as shown in FIGURE 3, a catch lever 29 may be provided. `Catch lever 29 is pivotally secured to a pedestal 30 lattached to base 38 of assembly 1. The catch lever 29 may be attached to pedestal 30 by a fastening means 31 which allows free pivotal movement of the catch lever. When the catch lever 29 is in the operative position, the seal between chamber 2 and chamber 3 is effected. During cleaning or threading, the catch lever 29 is pivoted to a position away from support arm 27 and above pedestal 30 to allow support arm 27 to be pivoted about pivot pin 28. As shown in FIGURE 3, terminal blocks 25 and 26 may be secured to support arm 27 by threaded fasteners 32.

Ifa visual display capability is required, a transparent phosphor screen 35 may be mounted within a clamping rim 36 on base 38 as shown in FIGURE 3. The transparent phosphor screen 35 may be aligned with the chamber 2 if -the writing assembly is moved laterally along line 4-4 thereby exposing the phosphor screen to charged particles. Bearing assemblies 59 which allow lateral movement are illustrated in FIGURES 4 and 5. The abovedescribed structure gives assembly 1 a recording means, the tape 5, as well as a visual display means, the screen 35, while still maintaining a pressure differential between chamber 2 and chamber 3.

FIGURE 4 illustrates the labyrinth seal as a part of the total assembly 1. Pivot pin 28 for support arm 27 is inserted through support pedestal 40. The pedestal is fixed to base 28 above aperture 4 and to a corner of support arm 27 to avoid interfering with tape 5. Catch lever 29 makes contact with support arm 27 on a planar surface 42 which is elevated above seal roller 7 to allow catch lever 29 to pivot freely about fastening means 31 without undesirable interference from other portions of the assembly.

Mountings and 51 are aligned with support pedestal 40 and terminal block 25 to avoid interference with tape 5. Since terminal blocks 25 and `26 must be in total contact with cradle 6, catch lever 29 is resilient to enable it to transmit force through a contact button 43. A thumb knob 44 is provided to facilitate pivoting of catch lever 29 which will incur substantial resistance as contact button 43 slides over planar surface 42.

lIf dirt were allowed to collect on guide cradle 6 at aperture 4, the recording on tape 5 would be impaired. To eliminate this possibility, a wiper 45 which is secured to support arm 27 by a fastener 46, is mounted on the underside of planar surface 42 and bears on circumferential depression 16 in seal roller 7. The wiper 45 removes any particles which have been transferred from tape 5 to the circumferential depression 16.

If the seal roller 7 were returned to an unaligned position after cleaning and threading, tape 5 lwould not be properly aligned with aperture 4. FIGURE 5 discloses means for assuring proper alignment comprising a locating pin 54 which is inserted through guide cradle 6 into an aperture 55 in terminal block 26. When the locating pin 54 is inserted into aperture 55, and the rounded surfaces of terminal blocks 25 and 26 are in contact with the cylindrical surface of cradle 6, the seal roller 7 is accurately positioned over aperture 4 in guide cradle `6 thereby limiting play along the axis of pin 28.

The moveable nature of assembly 1 gives it a valve-like characteristic which serves to control the flow of charged particles to the tape 5 or to the phosphor screen 35. This provision also allows the pressure in chamber 3 to be increased so that the pressure differential, maintained by a conventional pump (not seen) connected to chamber 2, between chamber 3 and chamber 2, can be as great -as l: 100,000 as may be desirable when threading tape 5 in chambers 3 and 13.

The bearing assemblies 59 which implement the valvelike characteristic are shown in FIGURE 5. The bearing assemblies 59 allow movement of the assembly 1 along line 4-4 thereby allowing the charged particles to communicate with tape 5 through aperture 4 or to communicate with phosphor screen 35 depending upon the position of the assembly. Each bearing assembly 59 comprises grooves 60 and bearing surfaces 61. A toroidalshaped member 62 made of a suitable elastic material such as neoprene is compressed between surfaces 61 and 60 to provide a seal so that gas cannot pass from chamber 3 into chamber 2 through the slidable bearing assembly.

In order to thread the assembly 1, catch lever 29 may be pivoted to a position overlying the pedestal 30. Support arm 27 is pivoted away from base 38 exposing guide cradle l6. The exposed guide cradle 6 may now be cleaned with relative ease prior to inserting tape 5 into circumferential depression 16 of seal roller 7. The tape is then depressed into the guide cradle 6 by pivoting support arm 27 toward base 38. Locating pin 54 may then be inserted into aperture 55 to assure proper alignment between tape 5 and aperture 4 by assuring proper alignment of seal roller 7.

Flanking guide rollers S and 9 support and position the tape 5 to allow unrestrained passage through guide cradle -6. As discussed above and illustrated in FIGURE 2, seal roller 7 under pressure provided by catch lever 29, maintains a seal with tape 5 and guide cradle 6 between the charged particle source chamber 2 and the tape handling chamber 3. Phosphor screen 35 may be positioned over aperture 4 by moving assembly 1 along on the bearing assemblies 59 thereby providing a visual display.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A charged particle writing system comprising a chamber maintained under low pressure and housing a source of charged particles, a chamber maintained at a considerably higher pressure than the first-mentioned chamber housing a tape handling system, and a seal assembly between the first-mentioned and second-mentioned chambers, the improvement lying in the seal assembly comprising:

a seal roller;

a guide cradle closely spaced to and in complementary relationship with said seal roller;

means for interspacing a tape between said seal roller and said guide cradle;

a base;

a support arm movably mounted on said base, said seal roller being mounted on said support arm, whereby one surface of a tape makes substantially sealing contact with said seal roller and said guide cradle when said seal roller is in operative relationship with said .guide cradle;

a locating pin inserted in said guide cradle;

a terminal block mounted on said support arm for mounting said seal roller to said support arm; an

aperture in said terminal block for receiving said locating pin inserted in said guide cradle to achieve proper tape positioning when said seal roller is in operative relationship with said guide cradle.

2. The charged particle writing system of claim 1 with the improved seal assembly including a resilient means associated with said support arm, said resilient means supplying suicient pressure to position said sealing roller and achieve a seal between a tape, said guide cradle, and said seal roller.

3. The charged particle writing system of claim 2 with the improved seal assembly including guiding posts and guide rollers mounted on said base flanking said seal roller for guiding a tape between said guide cradle and said seal roller.

4. The charged particle writing system of claim 1 with a phosphor screen mounted on said base and spaced from said, guide cradle, said seal assembly being movable to allow charged particle communication between said iirstmentioned chamber and said phosphor screen.

5. The system of claim 2 wherein said seal roller has a circumferential depression for guiding the tape.

References Cited UNITED STATES PATENTS 2,716,048 8/1955 Young 346-74 3,222,678 12/1965 Jones 346-74 3,23 6,943 2/1966 Mller 346-110 3,247,493 4/1966 Wolfe 340-173 3,345,639 10/1967 Dubbe 346-110 BERNARD KONICK, Primary Examiner. LEE I. SCHROEDER, Assistant Examiner.

U.S. Cl. X.R. 346-74, 313-89 

